 Well, first of all, I want to thank the Ancestral Health Society for the opportunity to talk here. The title is Are We Carnivore? Not where we carnivores, but in the present tense. So of course we are not carnivores running around hunting animals, but the question that I ask is are we still be biologically adapted to be carnivores. So and then if we are what does it mean in terms of protein consumption? What would be ideal sort of ideal or safe protein consumption for us, but that will come right at the end. First of all, let's see if we are carnivores. This chart here is adopted from a paper by Sylvia Smith and colleagues that was published in April, this year in science, and it shocked me and I hope that you will also be beautifully shocked. It describes the increase in body size or body weight in terrestrial animals, excluding bats. I don't know why they did that, but anyway. And they were really interested in the in the recent period relatively speaking of 126,000 years ago until now and the future, but they were kind enough to provide this data from 65 million years ago when the dialenazoles went extinct and the mammals started to become the dominant family. So at the beginning we were all we had the only rodents which weighed maybe a hundred grams or so and as you can see there is a constant increase in the size of mammals and this is to be expected. You think about the dinosaurs was so big and they were there for 120 million years or so. So the the earth can support big animals and apparently it happens as part of a larger scheme of evolution. So 62 million years later you find a group of a large mammals averaging 550 kilos and that's big. It's big because for that to happen you have to have quite a few species that weigh much more than 550 to offset the ones that weigh the rodents for instance. So so you're talking about and and we know that elephants that weigh about three times the size of elephants today. So huge, huge animals and quite a few, quite a few species. And so if you connect to the 2.5 that's the data they give. If you connect the 2.5 million to the 126 million there's your drop of about 80, over 80 percent. So because at that time it was only a hundred and this is in Africa and by the way Africa the decline in Africa was higher than the decline in other continents, although Africa is a big continent is not supposed to happen in big continents. So we don't know exactly what happened in the meantime between 2.5 and and 0.1. But we can guess because 2.5 million is when humans appeared. I'm talking humans, all the homos for me are humans. Homo habilis and then Homo erectus and Homo erectus appeared about 1.8 million years ago. And 1.5 million years ago, there's a big change in the hyper carnivores guild. A lot of species disappeared from this guild and the Verdelein and the Lewis speculate that this is because humans, Homo erectus in this case, entered the guild. And you see in the sites, in Homo erectus sites very large animals, elephants and similar, not similar size, small size, but very large sized animals with signs that of hunting, getting the first access to the animal. So I think it's quite convincing that that this decline in size, by the way today is 10. So you have today an average size, which is 2% of the size that the average size that was in two and a half million years ago. I can't think of any other reason why it would drop like that. So, but this is still an association. So we have to get to see if we can strengthen the evidence with some more. But first of all, first of all, I must spend some time discussing another implication of that slide and this is what it means to all the, for instance, the work of Lorene Codain. Because Lorene Codain gathered data on hunter-gatherers, recent hunter-gatherers, yeah, and I can tell you that the whole paleo-anthropology industry is using these numbers. But as you can see, he was using numbers for groups that were facing animals that on average are 2% of the size of the animals that were in the paleolithic. So it's just it's just not the same thing. So I think this is misleading. The whole ethnographic record as far as the quantity of meat in comparison to plants, I think we just forget about it. I'll show you some more, some more data on this. This is like two papers where they actually don't even take the average of the ethnographic data. They just take one tribe, the Hadza and use it to justify evolution two and a half million years ago. Anyway, if you look at the Hadza, I read a lot about the Hadza. If you look at the Hadza, they don't even have 10 kilograms average. If they don't have elephants in the territory, there are no rhinos, there are no hippos. These are animals that they used to hunt before. Now, this is the elephants is about a hundred year situation because as you know in Africa about a hundred years ago people started to kill elephants by the thousands to get ivory. So today you can find elephants only in game research and this is the situation with the Hadza and the chart shows the caloric return on hunting larger animals compared to small animals. So hunting a large animal and this is not the very large animal because this is again ethnographic information. So you're talking large animals is maybe, I don't know, a buffalo. So the caloric return on time is four times for larger animals compared to small animals and small animals are very close to tubers in the return. So that's in a situation like that the whole, they have to be reorganized. The whole thing has to be reorganized compared to the Paleolithic and and they do. Now Baobab tree is a very important tree for the Hadza. They consume 18% of their calories come from the fruit and the seeds and about 14% come from bees that make their home on these trees and the reason they use these trees is this is the highest tree in Africa it's about 30 meters high it can be. So they escape predators of the of the honey of course by being high. So about third of the non-meat. Now they are consuming about 60% non-meat and about 40% meat. So about half of the non-meat calories come from this tree. Well, it so happened that elephants don't like Baobab trees. And I'll just read you first of all about elephants and trees. It's a small, let me see if I can read that. African bush elephants in Kruger National Park uproot up to 1500 adult trees per elephant per year. Okay, these guys work for a day. Adult. And then what happens is that elephant reduce wood is species cover by 15 to 95% So really, and this is the name of the paper, elephants create savannas. So when there are no elephants sorry, so when there are no elephants the landscape changes completely and it so happens that the picture on the right is an elephant finishing off a Baobab tree. They drink the water, this tree contains a lot of water and in dry periods they like to drink the water so they just kill the tree. Game reserves notice that as the elephant population recover, the Baobab population declined. So in tourist like Baobab trees, maybe more than elephants, I'm not sure. So they got researchers to look into it. And if you read the paper they call elephants, they call Baobab predators. This is the name they sign to elephants. So just imagine a situation where the Hadza don't have these Baobab trees, but have elephants and rhinos and and other large animals and I leave you to guess what to think, how would their diet look like? So forget about this all this information about its irrelevant. So if we want to know what people ate, archaeology is the place and the answers are short about everything. Everything edible. So seeds and tubers and fruits and and of course everything that's it's alive but this is not really interesting for our question. The more interesting is what is the relation between the food, the animal food and the plant food and unfortunately I spent about six years reading thousands of papers in archaeology and the answer is not there. There's one that I have to give that is directly archaeology can supply some answers and this is the accumulation of nitrogen isotope 15. It gets accumulated as the trophic level go up so carnivores have more of it than herbivores. And what you do is you come to a site and you try to get cull again from the human remains, from the carnivores in the area, from the herbivores in the area and to measure the isotope 15 and in all these cases humans have the same amount as carnivores. So some cases even higher but there's some anyway. The objection that other researchers has to it is that still they could have eaten about 50% of plants they don't register so much because plants don't have a lot of protein. What I think they forget is that this protein comes with fat. So if it's an animal that has 50% protein and 50% fat there's not much room left for plants. Anyway this is what it is and so after spending so many years in archaeology I came to the conclusion that actually the answer is in biology. And I'm not a biologist so my interpretations are open to you know debate like any other interpretation. I ran it by a biologist Raffi Sert if you know some people know him and you know, but all the responsibility of course is mine. So I started to look for for papers that will give me some information about the level of carnivory from our own body. So you have genes, you have metabolism, you have morphology, pathology. I believe that I just scratched the surface. There are many more pieces of evidence that will be found in the future I'm sure. So here's the first one. Most of you know it I think. This is the structure of the stomach. Our our large intestine is 70% shorter than if we had chimpanzee, our size. And the small intestines are longer. So this structure is is really an adaptation in the direction of carnivores. And it's very significant because another question we can ask but the same really rephrase the question of carnivory is how specialized we are. What was our evolution towards specialization? Because nobody thinks that we are specialized to consume plants. So specialization in humans is if you find sign of specialization, it means specialization towards carnivory. And specialization is evident when food, when your your adaptation is actually preventing you from getting another type of food. Because you can have adaptations they don't. Let's say adaptation to running which I'll show later. Yeah, you can run, get more animals, but still doesn't interrupt your ability to to obtain plants. But this one actually is very very indicative because there are very few plants without a lot of fiber in the wild. So it immediately reduces the caloric exploitation that you can make for plants by a very significant amount. So I think this is quite a quite an in the eye. By the way, the the skull on the top is there to show that this adaptation was already happening in Homo erectus. And you can see it because the size of the mandible and the size and the shape of the teeth. The mastication system prepared the food for the gut. So if it's smaller then the food is more concentrated. Okay. It's not fibrous. Fibrous demands different type of flat, flat teeth to grind it. Anyway, this adaptation was already there apparently with the Homo erectus. Another type that is I think also quite well known is the adaptation to running that the Bramble and the Lieberman found. Of course, you don't run to get plants. They don't escape. So yeah, and also so they think it's an adaptation type of hunting that's called endurance hunting. It's debatable because endurance hunting demand very special conditions. Type of soil that you can see the tracks. It exists. People do it. But whether it was really the main method of hunting, I'm not sure. But it also adapts us to walking and walking. Efficient walking is very important. For a predator, for a carnivore, because the home range of carnivores is much higher than that of omnivores. So you have to deal with a larger home range. So here's another one. Another one that I think is quite known is this shoulder. The adaptation of shoulder. If you ask, if you get a chimpanzee to throw a stone, he will throw it like five meters, ten meters. He just sees his hands are built to climb trees and not to throw something. So we are adapted to throwing. This is the whole shoulder is adapted and there are changes. serious changes in the shoulder to allow us to throw. And this in a way is also an indication of specialization because this adaptation prevents us from climbing, not prevents totally, but interrupting us in climbing trees. So forget about the foods. Another adaptation, I hope I won't bore you with too many adaptations. I'm just giving part of them here. The rest are in my PhD thesis. So another adaptation, and this is this adaptation in my opinion can be also interpreted as a consumption, as an adaptation for consumption of large prey specifically. We have about three times to four or five times the amount of fat compared to chimpanzees. And we are lucky in the sense that carrying fat doesn't reduce our fitness in hunting and in escaping because we don't escape. We'll never ever run faster than a predator or faster than a prey. So we don't we don't use fast in fastness, no speed. So it allows us to carry larger reserves. A hunter gatherer, when you measure his daily expenditure, energetic expenditure and divided by the amount of fat that he has, can live about three weeks without eating. A woman can live double that amount. Women have more fat than men. So three weeks is actually, in my opinion, is adaptation to hunting of animals that are scarcer than smaller animals. Larger animals are less abundant. This is a law of nature. And so to get large animals, probably the intervals between the hunting is higher. So this is an adaptation to that as far as I'm concerned. The next one also is quite known. I will be very quick with it. You can spend some time on it. Apparently the number of copies of the salivary amylase gene, ME1, changes in societies, or it's high in societies, the consumed starch and is lower in societies that don't consume starch. Chimpanzees have two copies and we range from two to 16 copies. And this allows starch consumers to release the amylase enzyme and degrade the starch to sugar. Announcing to the pancreas that sugar is coming. The mere fact that we have this range actually points to a situation where it's not fixed. So normally genes that are there for a lot of time get fixed. And so it may point to the situation where it's a very short term adaptation. Another genetic adaptation is to the consumption of tubers. And only groups, the consumer, a lot of tubers have this adaptation. It adapts you to detoxify glycosides, and it adapts you to synthesize folic acid, which tubers are very poor. So, and by the way, this is more important than you think, because if you look at the papers of most of the people who support a high plant diet during the Paleolithic, they rely on tubers. They think this is what they ate, because tubers are not toxic. Tubers can be found throughout the year. Tubers, blah, blah, blah. But apparently we're not adapted to eat it. And by the way, the heads of themselves don't consume a lot of tubers. For them, it's the less preferable food, tubers. They like best honey, and then meat, and then I think this is a barbeque business. Okay, now from Paleo, from Pathology, Pathology. These are of course cavities from caries, and the earliest finding of this situation is in Morocco 15,000 years ago. So, it means to me that there was no high starch consumption before that, because these cavities are associated with high starch consumption. In this case, it was acorn. You can see on the right, these are the teeth and mandible of the recent Homo sapiens from Morocco 300,000 years ago. Look at the perfect teeth. And this is what you find in many teeth. There are quite a few teeth, because teeth preserve much better than bones. So there are thousands of teeth that were found in archaeological sites, and most of them are perfect. Okay. Now, come three adaptations that I love the most, because I don't have to interpret a lot. What the researchers did in all three is dividing this phenomena into groups. So carnivores have this type and omnivores have that type. And what do you know? Humans fall always into the carnivore group. The first one is aged weaning. We wean in two, two and a half years, and the chimpanzee wean at five to seven years. So carnivores wean early. And this is not surprising, because carnivores wean to a food that is very similar to the milk, to the mother milk. You have protein and you have fat. So, but primates wean them to consume starch and not starch, but fiber and sugars. Completely different diets, so they have to take much more time to adapt to it. So, as I said, humans fall right into the carnivore group and this is what the researchers, Pesuni and colleagues write. Our findings highlight the emergency of carnivory as a process fundamentally determining human evolution. Okay. Music to my ears. Confirmation bias. Another one that's something that you never expect or even bother to check is the number and size of the fat cells. It turns out that carnivores have a higher number of smaller fat cells to contain the same amount of fat. Omnivores have a lower number of larger fat cells. By the way, herbivores have also a carnivore pattern because they eat fat actually. In the end, what they get, what they feed on is short chain fatty acids. So, so there you have it and this is what's done in humans, by the way, have the highest number and the smallest cells. So, very, what? Very squarely in the predator, so I have to go fast. So, but I like to read it. Music. Humans are adopted to a diet in which lipids and proteins, rather than carbohydrates, make a major contribution to the energy supply. Okay, so again, okay, we'll be quick. Stomacosidity. Stomacosidity is also indicative of whether you are carnivore or herbivore or herbivore because carnivores have to deal with the higher level of pathogens and scavengers, of course, even higher level. So where are we? We had the highest level of acidity among the 50-something animals that were checked. So, the conclusion of the researchers was that we were maybe more scavengers than we thought. But actually, if you look at the humans, a very special kind of carnivore. They take the prey and they sit on it and they take it, they don't leave it where they find it. They take it to a central place and they consume it for days and weeks. An elephant can last for months, two months. Large animals can last for weeks, days. So, so it's like a sort of scavenging on your prey. That's why we have a large high load of pathogens and that's why it's an adaptation. And this is very expensive adaptation to carry to carry acid, high acidity in your stomach. First of all, to produce the acidity is very energetic, demanding process. And then you have to align the stomach with it. So, it's a very indicative, boy, this sounds fast. So, this is the summation of what I found, including other things that I did mention. I found two that could be interpreted against carnivore. That's debatable completely, but I don't want to go into them. Twelve that support carnivore. Seven that support low plant, like this T situation that doesn't prove carnivore, but it supports low plant. Eleven plus maybe four that support specialization. And ten that support that all these adaptations were already in Homo erectus. So, I have to get quickly today. Okay, I will just cut this one very short. Humans, and this is going back to archaeology. Humans are a very specialized hunter in the sense that they are targeting fat. And you can find it from four different patterns in the prey that you find in their sights. I won't go into it. It's very interesting, but maybe in another lecture. But they all prove very, very strongly that fat is like a must for them. I just give the last example, the last one, which is really crazy, extracting fat from bones. To extract fat from bones in paleolithic situation, you have to dig a hole, cover it with skin, break the bone into small pieces. This is not an easy job. It demands a lot of energy. And then you get a fire done. You bring stones. They have to be big stones because small stones don't hold to the heat. So you put them in the fire, and then when they are hot, you put them in the water. You boil the boil, and you wait, and like I'm sure some of you, at least I think many of you have actually done already, and the fat float. Now what happens is these stones break because they go from hot to cold, from cold to hot. So they get broken and then they're useless. So you have to get further, further away from the site to get these large stones. All of this to get something like 6% of the fat in the animal that is stored in the bones. So this actually happened. Only you see it only in the end of the paleolithic. And in my opinion it shows that they were very short of fat with smaller animals, but that's another lecture. So this is the last one. It's a chart that I'll try to explain. I hope you have time for that. The bottom line, the X axis, shows the amount of fat, caloric terms in the animal. So let's say an elephant has about 60% of the calories as fat and 40% as protein. A zebra will have about 40% as fat and 60% protein. So on the Y axis, you have the percentage of calories that you have to get from non-protein sources. So it's plants, carbohydrates and fat from plants, or fat from other animals which you use and you use only the fat. Why? Because we are limited in the amount of protein that we can consume. The limit is about between 35 and 50% of our calories. We don't know. Nobody knows. But there is a limit. It's proven that what's called the rabbit starvation, where people that feed on too much protein actually die. So let's say the limit is 50%. What it means is that if you catch an animal that's 50% fat and 50% protein, you are at zero. You don't need any supplement from other sources. You got all your calories. But if you get an animal that's 40% fat and 50% protein, you eat the 50%, but you're still short of fat to complete. Now, this is not 10%, but this is beside the point. It comes up to about 17%. And if you get a small deer, let's say, which is 30% fat, and by the way, I'm not talking about dry periods. Dry periods, these guys don't have more than 10% or 5% fat. Just imagine it's a nightmare. So, and then you have to complete like 30% from other sources. Now, this previous slide where I'll show you that they're so desperate for fat means that they could not get it from plants. If they could get it from plants, they were not so, and this concentration of fatty animals is energetically expensive. They hunt some kind of animals. They don't hunt others. They go around, they encounter an animal. It doesn't have fat. They just leave it. So it's very energetically expensive to have this kind of strategy. So it means to me that plants were very scarce. They did eat plants. I showed you in one of the first slides. But it means to me that they were always on the protein limit. Whatever it was, if it's 35% or if it's 50%, most of the time, I think almost 100% of the time, because protein is not a problem. You can get protein easy. Fat is the problem. And completing the 50% is the problem. So the conclusion. The conclusion is that we for about a million and a half years ate a lot of protein. We ate 35% to 50% of our calories from protein. What does it mean for us today? That's an open question. Whether it's actually ideal for us to be on the edge all the time, on the limit, I don't know. But it certainly points to safety. For me, the whole paleo template is a safety template. It's not supposed to point us to the ideal diet. It's supposed to teach us safety in a situation where we don't know a lot about it. So I'd say it is safe to eat large quantities, double. Today the average consumption is about 15% protein. I think in the States it's 12%. So it's quite safe to double your consumption of protein. 35% comes to about 4 grams per kilogram body weight. Just remember the RDA is 0.8. So how far are we? Now another aspect of it is that if you eat protein, you don't eat other things. And of course the benefit depends on what you exclude. Because what you include is quite safe. And I'm not talking about all the people that need, you know, the sarcopenia business and everything. So my conclusion is eat more protein. Thank you. Oh, I have a nice one. I have a nice one. I love elephants.